The present invention relates to downhole wellbore operations and, in particular, to systems and methods of permanently locking open a Sub-Surface Safety Valve (SSSV).
A typical oil or gas well includes a SSSV to provide the ability to shut off the flow of the oil and/or gas at a point below the surface to avoid an uncontrolled release of the oil and/or gas, or “blow out,” in the event of damage to surface components of the well. A SSSV typically includes a flapper valve configured to open downward and, when closed, to seal against a valve seat so as to prevent upward flow through the SSSV.
A Tubing Retrievable Safety Valve (TRSV) is one type of SSSV that is run and retrieved as part of the production tubing string. A TRSV may be located near the surface in a land-based well or at a depth of 1000 feet or more in a subsea well. A hydraulic control line typically runs in parallel to the production tubing and connects to the TRSV to control the operation of the TRSV. The flapper of the TRSV is held open when pressure is provided through the control line, and loss of pressure in the control line causes the flapper to close. A “slim-line” version of a TRSV provides a relatively large flow inner diameter in relation to the outer diameter of the TRSV body.
One problem sometimes encountered with a TRSV is that the mechanism of the TRSV may become damaged or clogged, for example, by debris within the oil or action of hot, corrosive oil, and as a result the TRSV no longer operates properly. Replacing a TRSV is a complex and difficult task and it is sometimes desirable to leave the malfunctioning TRSV in place and disable the TRSV by locking the flapper in an open position. One method of disabling a TRSV is to lock the flow tube of the TRSV in the extended position so that the flow tube retains the flapper in the open position. What is needed is a reliable means of opening the flapper, extending the flow tube, and then deforming the flow tube so as to interfere with other features of the TRSV thereby locking the flow tube in the extended position.